diff options
| author | Mark Wielaard <mjw@redhat.com> | 2013-10-06 17:04:07 +0200 |
|---|---|---|
| committer | Mark Wielaard <mjw@redhat.com> | 2013-10-07 11:16:27 +0200 |
| commit | 3dec3e110bb2a2453156868e1221dc8192399e3e (patch) | |
| tree | 65eb424f42bfd80f2bcc2b6a8d1a6d96df5e475a /libebl/libebl.h | |
| parent | 5dbbc5e32cc1fb3a7cf33e52e0bfc6f47097f3fe (diff) | |
| download | elfutils-3dec3e110bb2a2453156868e1221dc8192399e3e.tar.gz | |
backends: ppc_abi_cfi reg1 use DW_CFA_val_offset not DW_CFA_val_expression.
Register rules using expressions are stored using an offset from the
start of the .eh_frame or .debug_frame ELF section data. Since abi_cfi
rules aren't stored in those ELF sections they should use neither
DW_CFA_expression nor DW_CFA_val_expression. The only backend that used
DW_CFA_val_expression was ppc_cfi.c. It was easier to express the same
rule using DW_CFA_val_offset than to change the code to handle register
rules using expressions. On most architectures this did work by accident.
See the definition of struct dwarf_frame_register value in libdw/cfi.h to
see why. But on ia64 the abi_cfi data and actual frame data were placed
too far apart and caused a crash in tests/run-addrcfi.sh for ppc32.
Signed-off-by: Mark Wielaard <mjw@redhat.com>
Diffstat (limited to 'libebl/libebl.h')
| -rw-r--r-- | libebl/libebl.h | 5 |
1 files changed, 5 insertions, 0 deletions
diff --git a/libebl/libebl.h b/libebl/libebl.h index cae31c9b..990167a5 100644 --- a/libebl/libebl.h +++ b/libebl/libebl.h @@ -257,6 +257,11 @@ extern int ebl_syscall_abi (Ebl *ebl, int *sp, int *pc, before each CIE's initial instructions. It should set the data_alignment_factor member if it affects the initial instructions. + The callback should not use the register rules DW_CFA_expression or + DW_CFA_val_expression. Defining the CFA using DW_CFA_def_cfa_expression + is allowed. This is an implementation detail since register rules + store expressions as offsets from the .eh_frame or .debug_frame data. + As a shorthand for some common cases, for this instruction stream we overload some CFI instructions that cannot be used in a CIE: |